Service will not start
If a service will not start, the likely cause is that the port the service is allocated to is in use by another application. The common problem is that of a conflict with Microsofts SMTP server that is installed by default when you install IIS. Make sure the Simple Mail Transport Protocol (SMTP) service is disabled in the Services control panel.
MailEnable Receives email, but does not send any
The DNS you entered is probably incorrect. MailEnable needs a valid DNS in order to resolve a domain name to an IP address. Make sure the DNS IP address is a valid, working address.
MailEnable send email, but does not receive any
Make sure you have an MX record in the DNS for your domain. This is how remote machines find out your IP address.
MailEnable Cannot Resolve Domain Names
MailEnable requires access to a Domain Name Server (DNS) in order to resolve a domain name to an IP address.
Unsuccessful sends to HotMail, Yahoo, etc. but sending to others works
Some larger mail servers require that you have a reverse entry in your DNS. This is done to avoid the large amount of spam these places receive.
Mail Clients keep asking to enter password This can be caused by incorrect username/password, a configuration error on the client or a lock on the users mailbox directory.